The present invention relates to a charge pump circuit for driving N-channel MOS transistors.
As is known, for driving a load in the motor-car or in general in the industrial field, it is necessary to have driving components which may be power elements or not and should operate in an efficient manner. Nowadays, as driving elements, N-channel MOS transistors are preferred, as they require a lower integration area than analogous P-channel devices. As is also known, these N-channel MOS transistors are designed so as to have their drain connected to the positive supply and their source connected to the load, while their gate should be maintained at a higher voltage than the supply one, so as to assure an efficient and low-dissipation operation of the MOS transistor.
Furthermore for the DC mode, a fast charging of the gate of the MOS transistor is required, so as to assure fast responses of the system (i.e. fast turn-on of the MOS transistor). To this aim, charge pumps are already known which are ground referred to obtain a fast charging of the capacitance of the MOS transistor gate. However, these charge pumps have shown to be inadequte to simultaneous satisfying both requirements.